Baffle for hydraulic reservoir



Sept. 11, 1962 'r. E. MEAD BAFFLE FOR HYDRAULIC RESERVOIR Filed Jan. 6, 1959 ATTORNEYS.

3,053,233 BAFFLE FOR HYDRAULIC REERVOIR Theodore E. Mead, 1020 Michigan Ave, Wilmette, Ill. Filed Jan. 6, 1959, Ser. No. 785,274 4 Claims. (Cl. 12138) This invention relates to a baflle for a hydraulic reservoir such as are employed in hydraulic systems where liquid is actuated by gas pressure.

The invention finds utility in the operation of hydraulically-powered work cylinders, for example. The

hydraulic liquid is subjected to air pressure in a reservoir" or tank. Thus, there is an interface existing between a gas and a liquid, the liquid generally being oil and the gas being air.

In a situation like this, rapid flow of liquid into a reservoir such as air above the liquid level, will cause turbulence in mixing of air with liquid unless the depth and volume of liquid in the reservoir is so great as to decelerate and dissipate the inflowing stream before it can break the surface. In open hydraulic systems, Where the liquid is usually oil, and where volumes are restricted by mechanical limitations, turbulence causes aeration and foaming of the oil to a degree which interferes with the proper functioning of the system. A jet of oil passing up through a volume of oil, on breaking the surface, causes a fountain which carries the air bubbles back into the oil as it falls; conversely, a jet of air striking the surface of the oil breaks up into bubbles which tend to stay in suspension and soon cause undesirable foaming. The undesirability of this foaming can be readily appreciated when the liquid carrying the air bubbles is employed to move a piston in a Work cylinder. The expected movement does not develop because of the compressibility of the air entrapped in the hydraulic liquid.

Attempts have been made to overcome this problem by interposing a baflle in the stream of fluid entering the reservoir. Most often the reservoir is a cylindrical tank having an oil inlet at the bottom end and an air flow port in the top end. In the prior art, a flat plate was interposed in the inlet stream to deflect the oil 90 degrees and direct it up against the cylinder wall. At the top of this flow, it curls inwardly and tumbles into the pool of oil, carrying air with it. I have found that the previouslyemployed flat baffle plate, therefore, has. distinct limitations, especially where the oil speed exceeds a certain value.

It is, therefore, an object of this invention to provide an improved bafiie for a hydraulic reservoir. Another object is to provide a baflie for an oil reservoir which is not limited in operation to a restricted range of liquid velocities but which functions to prevent aeration at all velocities. Still another object is to provide a baffle for the structure described hereinbefore in which vanes are provided to impart a tangential or rotary motion to fluid entering the reservoir. Yet another object is to provide an improved battle for a hydraulic reservoir which is effective not only to prevent the development of gas bubbles within the reservoir, but actually serves to eliminate bubbles which may have entered the liquid at some other point in the system. Other objects and advantages of this application can be seen as this specification proceeds.

The invention, in an illustrative embodiment, will be described in conjunction with the accompanying drawing, in which- FIG. 1 is a fragmentary elevational view, partially in section, of a hydraulic system employing reservoirs and batfles embodying teachings of the invention;

FIG. 12 is an enlarged cross-sectional view of one of the reservoirs seen in FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2; and

FIG. 4 is a reduced perspective view of the interior baflling arrangement seen in FIG. 2.

In the illustration given, the numeral 10 designates generally a double-acting Work cylinder. As seen in FIG. 1, the cylinder 10 is equipped with the usual slidable piston 11. The piston 11 carries a piston rod 12 which extends through an end Wall 13.

The cylinder 10 is filled with hydraulic fluid (usually oil) and which is designated 14. The fluid 14 is introduced into cylinder 10 through conduits 15 and 16, which in turn are coupled to hydraulic reservoirs or tanks 17 and 18, respectively.

The tanks 17 and 18 are connected at their upper ends through conduits 19 and 20, respectively, with a four-way valve 21. The four-way valve 21 in turn has connections as at 22 to a source of compressed air and at 23 to a vent device.

The apparatus just described is well known to the art, as is its operation. Therefore, only a brief description is included. In the operation of the piston seen in FIG. 1, air is introduced into tank 18 through conduit 22, fourway valve 21, and conduit 20. This air drives the hydraulic liquid in tank 18 into the left-hand end of cylinder 10, moving piston 11 to the right. The displacement of piston 1-1 to the right causes hydraulic liquid 14 to be forced up through conduit 15 into tank 17. The introduction of additional hydraulic liquid into tank 17 results in forcing air out of tank 17 through conduit 19, fourway valve 21, and conduit 23 to the venting device (not shown).

Inasmuch as tanks 17 and 18 are substantially identical, only one is presented in larger scale in FIG. 2, this being designated by the numeral 17. The tank 17 includes a cylindrical casing 24 which is vertically disposed, i.e., the axis of cylindrical casing 24 extends vertically. The cylindrical casing 24- is equipped with endplates 25 and 26 at the upper and lower ends, respectively. The end plate 25 is equipped with a flow passage 27 adapted for the movement of air or other gas therethrough and which is connected through a suitable fitting 27a to air conduit 19. The lower endplate 26 is equipped with a liquid flow passage 28 which is adapted to be coupled to the hydraulic liquid line 15. The flow passages 27 and 28 may be located either olfcenter (i.e., the axis of casing 24), as shown, or on the axis, if desired.

Mounted within the cylindrical casing 24 is a baflle assembly generally designated 29 and which is seen apart from casing 24- in FIG. 4. The assembly 29 is seen to include an upper baflle 3t} and a lower baflle 31. Each baffle 3t) and 31 is centrally apertured for the receipt of a threaded rod or bolt 32. The rod 32 is equipped with nuts 33 at both ends thereof for immobilizing the baflles 3t} and 31 in spaced-apart relation.

Each baflle is equipped at the periphery thereof with a plurality of outwardly-directed vanes 34-. The vanes 34 may be provided by dividing the flat baflle plate into equal arcs (such as the eight shown) which are turned down in the form of ratchet teeth. Thus, the vanes 34 extend generally perpendicularly to the horizontally-disposed flat baffles 3d and 31. The ratchet teeth or vanes 34 extend between the baffle 30 or 31, as the case may be, and the end wall '25 or 26, respectively. Each vane 3'4 is disposed at an angle other than a right angle to a radial line drawn to it from the axis of the casing 24- and the outermost portion of the vane 34 abuts the inner wall of casing 24, as can be readily appreciated from a consideration of FIG. 3. One end 34a of each vane 34 is closer to the axis, i.e., rod 29, than the other end 34b,

as is designated in FIG. 3. Thus, the radial line drawn to end 34a forms an obtuse angle with the vane 34. The baffles, endplates and vanes cooperate to provide a chamber equipped with outlets tending to direct fluid in a tangential manner that results in imparting a circlular motion to the whole volume of the tankthis being illustrated in FIG. 4 by the circular arrows. The fluid motion is like a whirlpool, with the typical inverted cone shape of surface. Because of this, when the flow stops, the oil does not tumble inward on itself, but flattens out gradually as its rotation slows down. The higher the inlet speed of the liquid, the steeper the sides of the inverted cone.

The action just referred to not only prevents the formation of bubbles within the tank, but actually eliminates bubbles which may have entered the oil at some other point in the system. As in a centrifuge, the heavy matter works toward the outside, and the light matter stays near the center. Here, bubbles work toward the cone-shaped surface and are dissipated into the air.

In certain instances, it may be desirable to increase the spacing of the battle relative to its associated endplate. This is feasible so long as the lower bafiie plate is not completely out of the oil at the low level.

In assembling the device, a conventional tank 17 may have its upper endplate 2S removed through removal of nuts 24a which, in conjunction with bolts 24b, retain the endplates 25 and 26 in place on cylindrical casing 2.4. Thereafter, the device 29 can be inserted, the overall length between the baflies being just slightly greater than the distance between the endplates 25 and 26 so that the device 29 is compressively secured within the casing 24 in an immobilized condition.

I have found that the lower baffle 31 is especially eifective in preventing aeration of oil or other hydraulic fluid when the fluid is returned to the casing 24. The upper baffle plate 30 cooperates with the remaining structure of the assembly 29 in effectively immobilizing the lower bafile plate 31 and since the assembly 29 is symmetrical about a horizontal center line, there can be no error in assembling the equipment. Further, the upper bafile 3t imparts a desirable circular movement to the air flow.

While, in the foregoing specification, I have set forth an embodiment of the invention in considerable detail for the purpose of explaining the invention, many variations in these details may be perceived by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. In a hydraulic reservoir for a hydraulic cylinder and piston unit, a vertically-extending, closed-ended cylindrical tank defined by a cylindrical side wall and flat upper and lower end walls and equipped with an air flow port at its upper end wall and a liquid flow port in its lower end wall, means for supplying compressed air coupled to said air flow port, said liquid flow port being coupled to said hydraulic cylinder and piston unit, an improved batfie structure for said reservoir comprising:

(A) a plate-like baflle element positioned adjacent to but spaced from the lower end wall of said tank in covering relation with said liquid flow port, and

(B) means in said tank fixing said baffle element in position,

said baffle element including a body equipped with a plurality of generally radially-extending, circumferentially spaced-apart cuts,

said body being folded on itself between each cut along a line extending between the inner end of a given cut and a point on an adjacent cut spaced from the inner end thereof to provide horizontally elongated, depending integral portions defining a ratchet-like arrangement,

said depending portions abutting said cylindrical side wall along the height of the portion and said lower end wall along the length of the portion to define a plurality of circumferentially spaced-apart outlets constituting the only communication between the space below said baffle element with the space thereabove and with said outlets lying in generally radial planes to develop a conical flow of liquid issuing from said outlets.

2. The structure of claim 1 in which said tank is equipped with a similar bafile fixed therein adjacent said upper end wall in inverted relation relative to the lower baffle element.

3. The structure of claim 2 in which said fixing means includes a rod extending between said bafiies.

4. In a hydraulic reservoir for a hydraulic cylinder and piston unit, a vertically-extending, closed-ended cylindrical tank defined by a cylindrical side wall and flat upper and lower end walls and equipped with an air flow port at its upper end wall and a liquid flow port in its lower end wall, means for supplying compressed air coupled to said air flow port, said liquid flow port being coupled to said hydraulic cylinder and piston unit, an improved baffie structure for said reservoir comprising:

(A) a pair of plate-like baflie elements positioned adjacent to but spaced from the upper and lower end walls of said tank in covering relation with said flow ports, and rod means in said tank extending between said bafiie elements fixing said elements in position, each baflie element including a body equipped with a plurality of generally radially-extending, circumferentially spaced apart cuts, said body being equipped with laterally-extending portions extending between the inner end of each cut and a point on an adjacent cut spaced from the inner end thereof and defining a ratchet-like arrangement, said laterally-extending portions abutting said cylindrical side wall along the height of the portion and the adjacent end wall along the length of the portion to define a plurality of circumferentially spaced-apart outlets constituting the only communication between the space below said body with the space thereabove, with said outlets lying in generally radial planes.

References Cited in the file of this patent UNITED STATES PATENTS 1,783,813 Schneible Dec. 2, 1930 2,183,763 Brown Dec. 19, 1939 2,197,539 Hickman Apr. 16, 1940 2,256,524 McKelvey Sept. 23, 1941 2,422,357 Tourneau June 17, 1947 2,489,903 Kraft et al. Nov. 29, 1949 2,683,463 Flick July 13, 1954 

